Fluorinated carbon polymer composites

Abstract

Disclosed are structures comprising a composite of fluorinated particulate carbon dispersed in a polymer, the fluorinated carbon being present in an amount sufficient to reduce the dielectric constant of the composition, the structure also including electrical conductor patterns. The composite can be made conductive by irradiating it with an UV excimer laser.

Having thus described our invention, what we claim as new, and desire to secure by Letters Patent is: 
     
       1. A method for making a dielectric material of a fluoropolymer and fluorinated carbon comprising the steps of: mixing a supply of fluorinated carbon particles in a supply of fluoropolymer with the fluorinated carbon to fluoropolymer being in the range of 2% to 60% by weight, and wherein said fluorinated carbon particles contain from 28 to 64 atomic weight percent of fluorine;   treating the mixture to form a composite thereof;   laminating said composite at a pressure in the range from about 100-200 psi and at a temperature in the range from 350° to 390° C.; and   exposing an area of said laminated composite to UV excimer laser radiation at a fluence in the range from 50 to 1000 mJ/cm 2  to partially defluorinate the fluorinated carbon and render said exposed area of the composite electrically conductive.   
     
     
       2. A method as in claim 1 wherein said mixing step comprises adding fluorinated carbon particles to an aqueous suspension of fluoropolymer containing wetting agents and stirring to form a uniform dispersion. 
     
     
       3. A method as in claim 2 wherein said treating step comprises coating said dispersion onto a substrate and heating to a temperature in the range from 290° to 320° C. to remove the wetting agents. 
     
     
       4. A method as in claim 1 wherein said fluoropolymer is of a material selected from the group consisting of polytetrafluoroethylene, (perfluoroalkoxy), fluorocarbon resin, co-polytetrafluoroethylene perfluorodioxide, and combinations thereof. 
     
     
       5. A method as in claim 1 wherein said fluorinated carbon particles are of a material selected from the group consisting of fluorinated carbon particles, fluorinated graphite, and fluorinated coke, and combinations thereof. 
     
     
       6. A method as in claim 1 wherein said free-standing composite film is laminated between two heat resistant substrates at a temperature in the range of about 355°-380° C. and a pressure in the range of about 200-1500 psi. 
     
     
       7. A method as in claim 6 wherein said calendering step comprises calendering said co-coagulum between two rolls, at a pressure in the range from about 500 to 1500 psi, at least one time until a uniform thin film in the range from 0.01 to 0.5 mm thick is obtained. 
     
     
       8. A method as in claim 6 further comprising the step of laminating said free-standing composite film between two heat resistant substrates at a temperature in the range of about 355°-380° C. and a pressure in the range of about 200-1500 psi. 
     
     
       9. A method as in claim 1 wherein said mixing step comprises: mixing fluorinated carbon particles in a solution of fluoropolymer and fluorinated hydrocarbon solvent; and   said treating step comprises: milling the mixture to get a uniform dispersion; and   coating said dispersion on a substrate and evaporating the solvent to form a thin composite film.     
     
     
       10. A method as in claim 1 wherein said treating step comprises: melting said mixture in a hot melt extruder; and   extruding the molten mixture to a thin film.   
     
     
       11. A method as in claim 1 further comprising the step of mixing a supply of silica in the range of 5% to 45% by weight into said mixture of fluoropolymer and fluorinated carbon particles. 
     
     
       12. A method as in claim 1 wherein said fluorinated carbon particles have a fluorine content in the range from 30% to 70%.